1. Technical Field
The present invention relates to a liquid ejecting head such as an ink jet type recording head, and a liquid ejecting apparatus including a liquid ejecting head.
2. Related Art
A liquid ejecting apparatus is an apparatus that includes a liquid ejecting head which is capable of ejecting droplets of a liquid from a nozzle and ejects various types of liquids from the liquid ejecting head. Representative examples of the liquid ejecting apparatus include an image recording apparatus, such as an ink jet type recording apparatus (printer), which includes an ink jet type recording head (hereinafter, referred to as a recording head) and performs recording by ejecting ink droplets of a liquid ink from a nozzle of the recording head. In addition, such liquid ejecting apparatuses are used in ejecting various types of liquids such as a color material used in a color filter such as a liquid crystal display, an organic material used in an organic electro luminescence (EL) display, and an electrode material used in forming an electrode. The liquid ink is ejected from the recording head for the image recording apparatus, and a solution of each of red (R), green (G), and blue (B) color materials is ejected from a color material ejecting head for a display manufacturing apparatus. In addition, a liquid electrode material is ejected from a liquid material ejecting head for an electrode forming apparatus, and a bio-organic material solution is ejected from a bio-organic material ejecting head for a chip manufacturing apparatus.
In an example of the recording heads described above, a communication plate 95 is disposed between a pressure chamber substrate 92 where a pressure chamber 91 is formed and a nozzle plate 94 where a nozzle 93 is open as illustrated in FIG. 11. A communication hole 96, which allows communication of the pressure chamber 91 with the nozzle 93, is disposed in the communication plate 95. The pressure chamber substrate 92 and the communication plate 95, and the communication plate 95 and the nozzle plate 94 are bonded via an adhesive. The liquid adhesive is used to fill a gap between the substrates. In addition, an upper side (side opposite to the communication plate 95) of the pressure chamber 91 is sealed by an elastic film 97, and an active portion 99, which is displaced in response to a change of a piezoelectric element 98 (a type of pressure generator) bonded to the upper side, is formed. The recording head having this configuration generates a pressure change in the ink in the pressure chamber 91 as the active portion 99 is displaced when the piezoelectric element 98 is driven. By using the pressure change, the ink in the pressure chamber 91 is ejected from the nozzle 93 via the communication hole 96.
The pressure chamber substrate 92 described above is produced through wet etching of, for example, a silicon single crystal substrate whose surface is a (110) plane. Accordingly, the pressure chamber 91 is formed into a parallelogrammic shape when viewed from a bonding surface side between the pressure chamber substrate 92 and the communication plate 95. In the pressure chamber 91 described above, two acute angle portions are formed at corners on diagonal lines of the parallelogram. In addition, the communication hole 96 can also be produced through wet etching of the silicon single crystal substrate, and is formed into a parallelogrammic shape when viewed from a bonding surface side between the communication plate 95 and the nozzle plate 94.
A phenomenon of the adhesive moving to the upper side (side opposite to the nozzle plate 94) due to a capillary force when the substrates are bonded via the adhesive was confirmed in the recording head described above (refer to an arrow in FIG. 11). Specifically, the adhesive moved along wall surfaces of the pressure chamber 91 and the communication hole 96. Particularly, the movement of the adhesive was likely to occur in the acute angle portions of the pressure chamber 91 and the communication hole 96. When the adhesive moved along the acute angle portion and cured in a state where the adhesive reached the active portion 99 of the pressure chamber 91, the displacement of the active portion 99 was inhibited and the ejection characteristics of the ink ejected from the nozzle 93 (the amount and flying speed of the ink droplets) may be subject to variations. A step disposed on a side wall of the pressure chamber substrate 92 partitioning the pressure chamber 91 was proposed so as to suppress this inconvenience (for example, JP-A-2006-218716). In this manner, it was possible to prevent the adhesive that moved along the acute angle portion of the pressure chamber 91 from reaching the active portion 99.
However, the step that is disposed on the side wall of the pressure chamber as described above was not sufficient. For example, during the bonding of the pressure chamber substrate with the communication plate via the adhesive, the adhesive may move to the active portion, over the step on the side wall of the pressure chamber, depending on the viscosity of the adhesive in the liquid state, the contact angle of the adhesive in the liquid state with respect to the pressure chamber substrate, the variations of the application amount of the adhesive applied between the substrates, and the like. Accordingly, the variations of the ejection characteristics of the ink ejected from the nozzle could not be suppressed.